The present invention is for a rock bolter which drills holes and sets bolts for stabilizing the roof and walls of mines, and more particularly for a rock bolter which can set bolts into rough rock surfaces while remaining compact in overall size.
Rock bolters have been developed to drill holes and set bolts to stabilize rock walls in mines and similar excavations. One type of rock bolter is the turret rock bolter, which typically has two feed tracks. One feed track directs a rock drill as it advances toward a rock surface to bore a hole into which a bolt is to be set, while a second feed track directs a bolt driver as it is advanced toward the rock surface to set the bolt into the hole. The feed tracks are sequentially rotated into a work position where the drill or the rock bolter residing thereon is in alignment with a particular location on the rock surface, and the rock drill or bolt driver is then advanced along its feed track to the rock surface. First, the drill is placed in the work position and advanced to drill a hole in the rock surface at the desired location. The drill is then withdrawn from the hole, and the turret is rotated to place the bolt driver in the work position, aligned with the hole. The bolt driver is then advanced to set the bolt into the hole. A stinger assembly is usually employed to engage the rock surface to stabilize the turret during the bolt setting process, in which case the turret typically rotates about an axis extending through the stinger assembly.
In many instances, the rock surface into which bolts are to be set is uneven, which limits the ability to rotate the feed tracks when they are positioned in close proximity to the rock surface. In an attempt to overcome this problem, U.S. Pat. No. 4,497,378 teaches a turret rock bolter where the feed tracks are translated away from the rock surface before rotating to allow the turret to rotate when the feed tracks are spaced further from the rock surface.
FIG. 1 is a schematic representation of the basic elements of the turret rock bolter taught in the ""378 patent. The rock bolter has a turret 10 having a support base 12 which is connected to a boom 14 for positioning the turret 10. A first cylindrical member 16 is fixed to the support base 12 and has an anchoring point 18 on one end. When the boom 14 is moved to position the anchoring point 18 against a rock surface (not shown), the anchoring point 18 engages the rock surface to act as a stinger.
A pair of spaced-apart bearing brackets 20 are rotatably and slidably mounted on the first cylindrical member 16, and a feed track support 22 is fixed to the bearing brackets 20 so as to extend parallel to the first cylindrical member 16. A drill track 24 and a bolt driver track 26 are provided on the feed track support 22. A rock drill 28 is longitudinally movable along the drill feed track 24, while a bolt driver 30 is longitudinally movable along the bolt driver track 26. An advancing mechanism 32 is employed to selectively move the rock drill 28 and the bolt driver 30 along their respective feed tracks (24, 26). In the rock bolter of the ""378 patent, the advancing mechanism 32 employs a system of pulleys 34 to allow a single advancing piston 36 to move either the drill 28 or the bolt driver 30 when the other of the two is immobilized.
To translate the feed track support 22 away from the rock surface, providing greater space for rotation, a translating piston 38 is mounted to the first cylindrical member 16 and is rotatably mounted to the feed track support 22. When the translating piston 38 is extended, the feed track support 22 is moved such that the separation of the drill feed track 24 and the bolt driver feed track 26 from the rock surface is increased.
To pivot the feed track support 22 to position either the drill 28 or the rock bolter 30 in alignment with a work axis 40, a second cylindrical member 42 is fixed to the bearing brackets 20. A pivot link 44 is rotatably mounted on the first cylindrical member 16 and both slidably and rotatably engages the second cylindrical member 42. A pivot piston 46 is connected at one end to the support 12, and at the other end to the pivot link 44. By extending and retracting the pivot piston 46, the pivot link 44 is rotated with respect to the first cylindrical member 16. The second cylindrical member 42, the bearing brackets 20, and the feed track support 22 rotate with the pivot link 44, and thus the feed track support 22 is rotated to position either the drill 28 or the rock bolter 30 in alignment with the work axis 40.
While the rock bolter of the ""378 patent allows translating the feed tracks away from the rock surface to facilitate rotation, it requires a complex structure to accomplish such action. The rock bolter has multiple, widely spaced bearings, which complicates the task of keeping the bearings protected from dirt and adequately lubricated. Furthermore, the use of the translating piston 38 to translate the feed track support 22 toward and away from the rock surface can result in binding. Because the translating piston 38 is mounted to one end of the first cylindrical member 16, forces on the various bearings are unbalanced, and must be transmitted long distances through other elements of the structure. The slidable bearing between the pivot link 44 and the second cylindrical member 42 can be particularly problematic, since it is not only axially spaced apart from the translating piston 38, but is also positioned on a different axis and thus is highly subject to torque. Because the feed track support 22 must rotate with respect to the translating piston 38, all translation forces must be transmitted through the pivotable connection between these two elements, placing great strain on this connection.
Thus, there is a need for a turret rock bolter which allows translation of the feed track support while overcoming the deficiencies of the device discussed above.
The rock bolter of the present invention employs a turret assembly where a boom is employed to position the turret assembly at a desired location with respect to a rock surface. The turret assembly has a base which is connectable to the boom. The connection of the base to the boom may include one or more knuckles, roll actuators, or similar devices known in the art for further adjusting the position and orientation of the turret assembly. The base may also serve to support other elements of the rock bolter, such as a bolt magazine for supplying a number of bolts and bolt plates sequentially to the bolt driver, such as taught in U.S. Pat. No. 5,597,267.
The base has at least one base bearing, and preferably a pair of spaced-apart base bearings. The at least one base bearing slidably and rotatably engages a cylindrical member having a cylinder axis. The cylindrical member terminates in a cylinder first end region and a cylinder second end region. A pair of spaced-apart brackets are fixably connected to the cylindrical member, with the base residing therebetween. One of the brackets is fixed to the cylinder first end region, while the other is fixed to the cylinder second end region.
Attached to the brackets is a feed track support which extends parallel to the cylindrical member. The feed track support has a drill feed track and a rock bolter feed track mounted thereon, and the feed tracks can be formed as integral parts of the feed track support. A rock drill is longitudinally movable along the drill feed track, and typically is mounted to the drill feed track via a drill carriage. The drill has a drill steel for drilling a hole in the rock surface as the drill is advanced along the drill feed track. A bolt driver is longitudinally movable along the bolt driver feed track support, and typically is mounted to the bolt driver feed track by a bolt driver carriage. The bolt driver, when advanced along the bolt driver feed track, advances a bolt into a hole bored by the drill.
Preferably, the base is configured such that the feed track support faces the operator of the rock bolter to provide the operator clear visibility of the drill and the rock bolter during the bolt setting process.
An advancement mechanism is provided for selectively moving the drill and the bolt driver along their respective feed tracks. Such advancement mechanisms are known in the art, such as the mechanism taught in U.S. Pat. No. 4,497,378 and discussed above, which employs single actuator for advancing both the drill and the bolt driver.
A jack is provided, having a jack body with at least one jack bearing which is rotatably mounted on the cylindrical member between the pair of brackets, and thus is rotatable relative to the base about the cylinder axis. The at least one jack bearing is also slidably engaged with the cylindrical member. The jack has at least one extendable piston which can be extended from the jack body and is connected to one of the brackets attached to the cylindrical member.
Means are provided for limiting translation between the at least one jack bearing and the at least one base bearing of the base such that the jack is allowed only very limited or, more preferably, no translational motion with respect to the base. Thus, when the cylinder translates relative to the base, it also translates relative to the jack body as well. The means for limiting translation of the at least one jack bearing with respect to the at least one base bearing can be provided by various means, such as by employing paired bearings positioned on either side of another bearing and constrainably engaging it either directly or via spacers, or by providing a bracket on either the base or the jack positioned to constrain the translational motion of a bearing. Preferably, a pair of base bearings are employed with a single jack bearing positioned therebetween and constrained thereby. In addition to providing a simple structure for constraining translational motion of the jack with respect to the base, the pair of base bearings and the jack bearing can be positioned adjacent to each other to provide reduced exposure of the individual bearings to dirt and debris.
Since translation of the jack body with respect to the base is limited, extending or retracting the at least one piston of the jack relative to the jack body provides a motivating force to translate the cylindrical member relative to the base and the jack. Preferably, the jack is a dual-action jack, having a pair of opposed pistons extending from either end of the jack body and moving in coordination, the opposed pistons each being attached to one of the pair of brackets. The use of opposed pistons provides more balanced forces on the translating elements to minimize binding. In all cases, when the at least one piston of the jack is activated, it moves the brackets relative to the one or more jack bearings, and the cylindrical member which is affixed to the brackets is moved longitudinally relative to the base. The feed tracks, which are fixed relative to the cylindrical member, are thus moved toward and away from the rock surface.
Since the at least one piston of the jack is attached to the brackets which are in turn affixed to the cylindrical member, the jack rotates with respect to the base about the cylinder axis in coordination with the cylindrical member.
A stinger assembly is provided, which is brought into engagement with the rock surface to stabilize the base during the drilling and bolt setting process. The stinger assembly is connected to the base either by attaching it thereto or by linking the stinger assembly to the base so as to avoid translational motion of the base in a direction parallel to the cylinder axis of the cylindrical member. The stinger assembly preferably has a stinger fixed portion which includes a stinger support structure that is affixed to either the base or the jack. It is further preferred for the stinger support structure to be configured to provide engagement with the rock surface at a point which lies along the cylinder axis.
Preferably, the stinger assembly has a stinger extendable portion which is extendably attached to the stinger fixed portion and terminates in a rock-engaging pad which is advanced toward the rock surface when the stinger extendable portion is extended. Preferably, the extension of the stinger extendable portion is provided by a linear actuator operating between the rock-engaging pad and the stinger support structure to eliminate the need to position the rock-engaging pad against the rock surface solely by motion of the boom. When the stinger support structure is mounted to the jack, it is preferred for the rock-engaging pad to be rotatable with respect to the stinger fixed portion.
A pivot actuator is operably connected between the base and the jack. When activated, the pivot actuator rotates the jack relative to the base about the cylinder axis. Since the feed track support is fixed to the brackets which in turn are affixed to the at least one piston of the jack, the feed track support rotates with the jack. Thus, the pivot actuator serves to rotate the feed track support to selectively place either the drill or the bolt driver in alignment with a desired location on the rock surface where the rock bolt is to be placed. When the drill has been positioned, it can be advanced along the drill feed track to bore a hole in the rock surface at the desired location. After the drill is withdrawn, the pivot actuator is activated to rotate the feed track support to place the bolt driver in alignment with the hole, and the bolt driver can thereafter be advanced to insert a bolt into the hole.
In one preferred embodiment, the pivot actuator is provided by a pivot linear actuator which is pivotably connected at one end to the base and at the other end to the jack. The pivot linear actuator is offset from the cylinder axis, and rotates the jack relative to the base as the pivot linear actuator is extended and retracted.
In use, the boom of the rock bolter is employed to position the turret assembly in a desired location and orientation relative to the rock surface, and the stinger assembly is engaged with the rock surface. When the stinger assembly includes a stinger extendable portion, the boom need only position the stinger assembly in close proximity to the rock surface, and the stinger extendable portion is then extended to engage the stinger assembly with the rock surface. At this time, the drill is positioned by the pivot actuator in alignment with the desired location for placement of the bolt if it is not already so aligned. If the jack is positioned so as to place the feed tracks at a substantial separation from the rock surface, the jack is activated to move the feed tracks in closer proximity to the rock surface.
The drill is then advanced along the drill feed track to bore a hole into the rock surface at the desired location. The drill is then withdrawn from the rock surface along the drill feed track and, if necessary, the jack is activated to move the feed track support away from the rock surface. If the rock surface is relatively flat, and there is sufficient space in close proximity to the rock surface to rotate the feed track support, withdrawal of the feed track support away from the rock surface is not required.
To move the bolt driver into alignment with the bolt hole, the pivot actuator is activated to rotate the jack and feed track support about the cylinder axis. The jack is then activated, if necessary, to bring the bolt driver feed track into close proximity to the rock surface, and the bolt driver is advanced to insert the bolt into the hole bored by the drill.